We have a HP PROLIANT DL160 G6 as a development server. Recently we decided to upgrade the memory and but this one. So we finish with 2 modules of 2GB that came with the server and the new module of 4 GB.

We tried to install the three of them, but the server fail to start. What could be happening? With only the new one installed it works as normal.

I've been reading a lot about it, but I fail to see the problem. Apparently all the modules have the same speed, the three of them are Registered and the HP guide doesn't say anything about installing an even number of modules.

Somebody has any clue?

The server doesn't boot, so I doesn't have any text error to share. It start doing a lot of noise as normal, but doesn't show anything in the screen and get stuck there.